fix: remove mcp-types from app server protocol (#4537)

We continue the separation between `codex app-server` and `codex
mcp-server`.

In particular, we introduce a new crate, `codex-app-server-protocol`,
and migrate `codex-rs/protocol/src/mcp_protocol.rs` into it, renaming it
`codex-rs/app-server-protocol/src/protocol.rs`.

Because `ConversationId` was defined in `mcp_protocol.rs`, we move it
into its own file, `codex-rs/protocol/src/conversation_id.rs`, and
because it is referenced in a ton of places, we have to touch a lot of
files as part of this PR.

We also decide to get away from proper JSON-RPC 2.0 semantics, so we
also introduce `codex-rs/app-server-protocol/src/jsonrpc_lite.rs`, which
is basically the same `JSONRPCMessage` type defined in `mcp-types`
except with all of the `"jsonrpc": "2.0"` removed.

Getting rid of `"jsonrpc": "2.0"` makes our serialization logic
considerably simpler, as we can lean heavier on serde to serialize
directly into the wire format that we use now.

codex-rs/core/src/auth.rs

@@ -15,7 +15,7 @@ use std::sync::Arc;
 use std::sync::Mutex;
 use std::time::Duration;
 
-use codex_protocol::mcp_protocol::AuthMode;
+use codex_app_server_protocol::AuthMode;
 
 use crate::token_data::PlanType;
 use crate::token_data::TokenData;

codex-rs/core/src/client.rs

@@ -6,8 +6,8 @@ use std::time::Duration;
 use crate::AuthManager;
 use crate::auth::CodexAuth;
 use bytes::Bytes;
-use codex_protocol::mcp_protocol::AuthMode;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_app_server_protocol::AuthMode;
+use codex_protocol::ConversationId;
 use eventsource_stream::Eventsource;
 use futures::prelude::*;
 use regex_lite::Regex;

codex-rs/core/src/codex.rs

@@ -19,7 +19,7 @@ use async_channel::Sender;
 use codex_apply_patch::ApplyPatchAction;
 use codex_apply_patch::MaybeApplyPatchVerified;
 use codex_apply_patch::maybe_parse_apply_patch_verified;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use codex_protocol::protocol::ConversationPathResponseEvent;
 use codex_protocol::protocol::ExitedReviewModeEvent;
 use codex_protocol::protocol::ReviewRequest;
@@ -3301,7 +3301,7 @@ mod tests {
     use crate::state::TaskKind;
     use crate::tasks::SessionTask;
     use crate::tasks::SessionTaskContext;
-    use codex_protocol::mcp_protocol::AuthMode;
+    use codex_app_server_protocol::AuthMode;
     use codex_protocol::models::ContentItem;
     use codex_protocol::models::ResponseItem;
 

codex-rs/core/src/config.rs

@@ -23,12 +23,12 @@ use crate::openai_model_info::get_model_info;
 use crate::protocol::AskForApproval;
 use crate::protocol::SandboxPolicy;
 use anyhow::Context;
+use codex_app_server_protocol::Tools;
+use codex_app_server_protocol::UserSavedConfig;
 use codex_protocol::config_types::ReasoningEffort;
 use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::config_types::SandboxMode;
 use codex_protocol::config_types::Verbosity;
-use codex_protocol::mcp_protocol::Tools;
-use codex_protocol::mcp_protocol::UserSavedConfig;
 use dirs::home_dir;
 use serde::Deserialize;
 use std::collections::BTreeMap;

codex-rs/core/src/config_profile.rs

@@ -22,7 +22,7 @@ pub struct ConfigProfile {
     pub experimental_instructions_file: Option<PathBuf>,
 }
 
-impl From<ConfigProfile> for codex_protocol::mcp_protocol::Profile {
+impl From<ConfigProfile> for codex_app_server_protocol::Profile {
     fn from(config_profile: ConfigProfile) -> Self {
         Self {
             model: config_profile.model,

codex-rs/core/src/config_types.rs

@@ -313,7 +313,7 @@ pub struct SandboxWorkspaceWrite {
     pub exclude_slash_tmp: bool,
 }
 
-impl From<SandboxWorkspaceWrite> for codex_protocol::mcp_protocol::SandboxSettings {
+impl From<SandboxWorkspaceWrite> for codex_app_server_protocol::SandboxSettings {
     fn from(sandbox_workspace_write: SandboxWorkspaceWrite) -> Self {
         Self {
             writable_roots: sandbox_workspace_write.writable_roots,

codex-rs/core/src/conversation_manager.rs

@@ -13,7 +13,7 @@ use crate::protocol::Event;
 use crate::protocol::EventMsg;
 use crate::protocol::SessionConfiguredEvent;
 use crate::rollout::RolloutRecorder;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use codex_protocol::models::ResponseItem;
 use codex_protocol::protocol::InitialHistory;
 use codex_protocol::protocol::RolloutItem;

codex-rs/core/src/error.rs

@@ -1,7 +1,7 @@
 use crate::exec::ExecToolCallOutput;
 use crate::token_data::KnownPlan;
 use crate::token_data::PlanType;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use codex_protocol::protocol::RateLimitSnapshot;
 use reqwest::StatusCode;
 use serde_json;

codex-rs/core/src/git_info.rs

@@ -2,7 +2,7 @@ use std::collections::HashSet;
 use std::path::Path;
 use std::path::PathBuf;
 
-use codex_protocol::mcp_protocol::GitSha;
+use codex_app_server_protocol::GitSha;
 use codex_protocol::protocol::GitInfo;
 use futures::future::join_all;
 use serde::Deserialize;

codex-rs/core/src/message_history.rs

@@ -30,7 +30,7 @@ use tokio::io::AsyncReadExt;
 use crate::config::Config;
 use crate::config_types::HistoryPersistence;
 
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 #[cfg(unix)]
 use std::os::unix::fs::OpenOptionsExt;
 #[cfg(unix)]

codex-rs/core/src/model_provider_info.rs

@@ -6,7 +6,7 @@
 //!      key. These override or extend the defaults at runtime.
 
 use crate::CodexAuth;
-use codex_protocol::mcp_protocol::AuthMode;
+use codex_app_server_protocol::AuthMode;
 use serde::Deserialize;
 use serde::Serialize;
 use std::collections::HashMap;

codex-rs/core/src/rollout/recorder.rs

@@ -6,7 +6,7 @@ use std::io::Error as IoError;
 use std::path::Path;
 use std::path::PathBuf;
 
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use serde_json::Value;
 use time::OffsetDateTime;
 use time::format_description::FormatItem;

codex-rs/core/src/rollout/tests.rs

@@ -18,7 +18,7 @@ use crate::rollout::list::Cursor;
 use crate::rollout::list::get_conversation;
 use crate::rollout::list::get_conversations;
 use anyhow::Result;
-use codex_protocol::mcp_protocol::ConversationId;
+use codex_protocol::ConversationId;
 use codex_protocol::models::ContentItem;
 use codex_protocol::models::ResponseItem;
 use codex_protocol::protocol::CompactedItem;